Involvement of long non-coding RNAs in pear fruit senescence under high- and low-temperature conditions

Pear fruit senescence under high- and low-temperature conditions has been reported to be mediated by microRNAs. Long non-coding RNAs (lncRNAs), which can function as competing endogenous RNAs that interact with microRNAs, may also be involved in temperature-affected fruit senescence. Based on the transcriptome and microRNA sequencings, in this study, 3 330 lncRNAs were isolated from Pyrus pyrifolia fruit. Of these lncRNAs, 2 060 and 537 were responsive to high- and low-temperature conditions, respectively. Of these differentially expressed lncRNAs, 82 and 24 correlated to the mRNAs involved in fruit senescence under high- and low-temperature conditions, respectively. Moreover, three lncRNAs were predicted to be competing endogenous RNAs (ceRNAs) that interact with the microRNAs involved in fruit senescence, while one and two ceRNAs were involved in fruit senescence under high- and low-temperature conditions, respectively. A dual-luciferase assay showed that the interaction of an lncRNA with a microRNA disrupts the action of the microRNA on the expression of its target mRNA(s). Furthermore, four alternative splicing-derived lncRNAs interacted with miR172i homologies (Novel_88 and Novel_69) to relieve the repressed expression of their target and produce an miR172i precursor. Correlation analysis of microRNA expression suggested that Novel_69 is likely involved in the cleavage of the pre-miR172i hairpin to generate mature miR172i. Taken together, lncRNAs are involved in pear fruit senescence under high- or low-temperature conditions through ceRNAs and the production of microRNA.